El campo de esfuerzos mesozoico-cenozoico en Tasmania a partir del análisis poblacional de fallas

Resum

With the aim to contribute to the knowledge of the tectonic evolution of the Tasmanian Passage, approximately 1000 faults distributed in 44 sites located in metamorphic, igneous and sedimentary rocks of ages between the Cambrian and the Quater- nary have been measured in Tasmania. The fault population analysis has been carried out using the methods of Etchecopar, y-R, Right Dihedral and Stress Inversion. The fault orientation analysis shows a predominant orientation ESE-WNW and secondary directions NE-SW, NW-SE and N-S. In general, the most of the fault planes dips are subvertical. Considering the faults movement sense, 313 dextral faults, 194 sinistral faults, 422 normal faults and 62 reverse faults have been identified. Dextral faults show an ESE-WNW orientation with subvertical dip. Sinistral faults have a predominant orientation N-S and dip also subvertical. Normal faults have a main NW-SE orientation and a NE-SW secondary direction with a modal dip value of 65°. Reverse faults have a predominant NE-SW direction with two modal dip values of 35° and 70° respectively. The σ1 orientation shows a dominant NW-SE direction. Moreover, another common stress regime is characterized by a preferentially NE-SW σ3 orientation (with σ1 vertical). The σy direction is dominantly NW-SE, although it shows a secondary mode with NE-SW orientation.